Maybe use a vm on some random cloud service?
Or better yet, use a university computer.

On Sun, May 19, 2024 at 5:43 PM Shlomo Solomon <shlomo.solo...@gmail.com>
wrote:

> I teach computer networking and the latest assignment I gave my
> students was to use Python and Scapy to emmulate traceroute. The code
> is simple:
>  - send an ICMP packet with TTL = 1 which will fail but return the
> first hop address
>  - continue sending ICMP packets - each time increasing the TTL to get
> the next hop
>  - if the ICMP reply is NOT an error, we have arrived.
>
> None of my student submissions worked, which was strange, so I tried my
> own code which I know is correct.
> It also did not work.
> The error messages arrive for each hop, but it seems that the NO ERROR
> message (when the destination is reached) is not arriving.
> I also checked with Wireshark and see error replies (as I should) for each
> hop, but then (when I assume I have reached the destination) there is
> no reply.
>
> I then tried disconnecting my computer from my ISP and connected via a
> Hotspot on my phone - PROBLEM SOLVED.
>
> So this seems to be a problem with my ISP (019) blocking some traffic.
> But I don't know what the next step is.
> If I call customer service, I'm sure no-one will understand what I want.
>
> BTW - ping and the "real" traceroute work fine.
> I also looked at router settings, but did not find anything suspicious.
>
> Can anyone suggest how to explain my problem to my ISP?
>
> ALSO - if there is anyone using 019, I would be happy to send my code
> for testing to verify that this is really a problem with 019.
>
>
>
> --
> Shlomo Solomon
> http://the-solomons.net
> Claws Mail 4.0.0 - KDE Plasma 5.24.7 - Kubuntu 22.04
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